Introduction

Myelodysplastic syndrome is a group of clonal disorders characterized by ineffective and dysplastic hematopoiesis.

  • Slow progression.
  • Mostly appears in older adults (>70).
  • The bone marrow hypercellular, but there is pancytopenia.
  • Tends to progress to AML.
  • Most cases are primary, but can also appear secondary to chemotherapy or ionizing radiation.
  • Characterized by distinct mutations in the hematopoietic stem cells, most frequently in genes involved in DNA methylation (TET2, DNMT3A, IDH1/2) and RNA splicing (ASXL1, EZH2).
    • The DNA methylation mutations appear in other malignancies, but the RNA splicing is rare outside of MDS.
    • Transformation of MDS to AML is typical in ASXL1 mutations.

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